devel/py-jsonschema: Fix build with setuptools 61.0.0+

error: Multiple top-level packages discovered in a flat-layout: ['json', 'jsonschema'].

To avoid accidental inclusion of unwanted files or directories,
setuptools will not proceed with this build.

If you are trying to create a single distribution with multiple packages
on purpose, you should not rely on automatic discovery.
Instead, consider the following options:

1. set up custom discovery (find directive with include or exclude)
2. use a src-layout
3. explicitly set py_modules or packages with a list of names

To find more information, look for "package discovery" on setuptools docs.

• Error code 1

With hat: python